Capgras Syndrome
by Cryptix
Summary: When a very strange body is sent to St. Bart's for research, an alien menace is again unleashed, and it's up to Sherlock, with the help of John, Molly, and a handful of others, to keep it from spreading. Can Sherlock Holmes handle the perfect mimic?


_(′käp·grəz ′sin′drōm)_

_(_psychology_) A misidentification disorder in which a person holds a delusion that a friend, spouse, parent, or other close family member has been replaced by an identical-looking impostor._

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><p>Herman Manchester, a balding, middle-aged accountant with three ex-wives and a gambling problem, died under suspicious circumstances on a Tuesday. In doing so, he may have inadvertently saved the world.<p>

That very morning had found the halls of St. Bart's hospital once again invaded by their perennial interloper, the detective Sherlock Holmes. He was handling a case of an impossible burglary which he had become convinced hinged on the chemical makeup of a carpet stain, and required the use of Barts' laboratory equipment to carry out his theory. He arrived, however, to find that his favoured lab was locked tight.

This was not entirely unusual. Sherlock checked the time and went to enact his usual fallback plan. He being Sherlock Holmes, his usual fallback plan was not 'go use a different lab', but rather, 'go bother the director until I get access to _my_ lab'. That the director was oddly fond of him and very receptive to manipulation just helped things along.

As he entered the office, morgue director Molly Hooper looked up, smiled, and shuffled the papers she was studying. "Sherlock! Hi."

"Molly," he greeted, his train of thought taking a detour as he looked her over, taking in the pencil securing her mousy hair in a bun, the utter lack of makeup to hide the purple under her eyes. She made a valiant effort not to fidget under his gaze, until he said, "What aren't you supposed to show me?"

She looked away and smoothed a stray hair behind her ear. "I- I uhm - what do you mean?"

Sherlock moved forward, his voice cool and precise as ever. "Molly. Your eyes are tired and your clothes are rumpled - you worked late last night, slept in your office, haven't had time to change. There's a mark on your cheek where you accidentally brushed it with the uncapped pen. This indicates that you were doing paperwork. You rearranged your papers when I walked in, your voice was strained, and your expression guilty. Add to that the extra personnel in the lower level who all bear obvious signs of government training, and clearly," and he leant on her desk to say this part, "a body was transferred here last night, a strange body, and you want to show it to me, but you're conflicted because you're under a confidentiality agreement."

Molly managed to meet his eyes for about a half-second before blushing and diverting her gaze again. "They've restricted the area. Only authorized personnel, no civilians. I'm supposed to say it's for a safety inspection."

"When, in reality...?"

Molly ran through the pros-and-cons list in her head, trying to weigh the likelihood of getting caught against the likelihood of her actually saying 'no' to Sherlock Holmes. She gasped at the feeling of cold fingertips on her chin, and looked up to find a slight smile on his pale lips, those perfect eyes crinkling in a way that looked almost genuine, like actual affection. "You know, I think the disheveled look suits you. It's more natural."

Oh, damn him. _Damn_ him.

"They have a half-hour break scheduled for 9. Bring John."

And damn her for letting it work.

_x-X-x_

Herman Manchester's body was brought into the morgue at 5:30 that night. At 6, a greyish-dark coroner led Detective-Inspector Greg Lestrade, Detective-Sergeant Sally Donovan, Doctor John Watson, and Sherlock Holmes to the body and explained what the preliminary reports indicated. After Sherlock had contradicted his report for the third time, the coroner gave up and left, leaving Sherlock and John to examine the body while the police-folk stood by and tried not to look quite as useless as they felt.

This was how they came to be there at 6:08, when the silence of the basement level was broken by a terrified scream. Sherlock looked up sharply from the dead man's knees, looked at John. "Molly," they said in unison, and both bolted for the door.

The hall outside the morgue was empty. Sherlock lead the way to the next, just as empty, the echoes of the scream already faded back into silence, and Sherlock paused, his head cocked to one side like a dog as he listened. Lestrade and Donovan's footsteps sounded loud behind them; John held up a hand before they could ask any questions. When Sherlock began moving down the hall again, they followed.

Sherlock was nearly on top of the door marked 'supplies' when it swung open, and Molly let out a startled scream. "Oh, god, it's you!" she cried in relief. The morgue director looked terrified, her eyes wide and skin pale, breathing in frantic bursts; and she was clutching a fire axe to her chest in a white-knuckled deathgrip.

"Molly?" John ventured, in his comforting Everything's-Okay-I'm-A-Doctor voice.

Sherlock, for once sounding genuinely concerned, added, "Molly, what's happened?"

Molly's eyes darted to a further door, one with a keypad beside it. "He's - he's killing them. He's killing them! But it isn't him - he's a - a monster, his face was a mouth and there were these tendrils, everywhere, and he sprayed something-"

Her rambling came to a sudden halt when the door down the hall opened, and before anyone could react, she darted into the middle of the hall and brandished the axe. A trim copper-bearded man in a white medical coverall put his hands up.

"You!" Molly cried. "It was you - it was him!" she added over her shoulder. "He was - you were killing them. Don't come any closer!"

The man visibly swallowed. "Miss Hooper, I understand that you're very confused right now."

"Confused! Oh, don't give me that. I know what I saw. I know - I saw you in there. I saw what you are."

"I am a doctor," the man said, deliberate and careful. "My name is James Ackerman. We're working with some volatile compounds in there, Miss Hooper, I'm afraid you might have breathed someth-"

"_I am perfectly rational!_" Molly shouted. The edge of hysteria didn't exactly inspire confidence.

Ackerman cast a helpless glance past her - _she's clearly mad, would someone please help?_

Behind Molly's protective stance, the two Yarders and one doctor shared a look - Sherlock continued to shift his focus between Molly and Ackerman, and failed to notice the silent communication at his elbow. John breathed out, Lestrade pursed his lips, and Sally narrowed her eyes, and all three of them nodded reluctantly.

"Molly," John said gently, as Lestrade and Sally began to surreptitiously change position. "Molly, sweetie. Why don't you put the axe down, and let's figure-"

Molly jerked around to look at him as if he'd just announced that he bit the heads off puppies for fun. "You don't believe me?" She glanced at Sally and Lestrade, and in a burst of adrenalin-fueled agility, spun and jumped back and put her back to the wall, all of them now in her sight. Her grip on the axe was starting to shake.

"Molly, please, calm down," Lestrade said.

"Don't - you have to believe me," she pleaded. "Don't fall for it. He looks human, but he's not - he was-" Her eyes lit up, and she turned a sudden feral grin on Ackerman. "That's it! Let them in. Let the detectives look at the lab, if you've got nothing to hide."

Ackerman shook his head. "Out of the question."

Molly laughed. "Of course it is! Of course! You don't want them to see what you've done."

"This area is off-limits except to authorized personnel. The insistence of a hysterical director does not equate to authorization."

"_She_ has authorization," Sherlock's smooth voice interjected, as flat and calm as if nothing strange at all were happening. "Otherwise she couldn't have come in and breathed in anything, could she?"

Ackerman shrugged. He looked frustrated. "She has the door code. She's not really authorized, but as the director we can't just cut her out."

"Of course." Sherlock stepped over to Ackerman, ducking his head so that he could speak to the man in confidence.

"Don't touch him!" Molly snapped, brandishing again at Ackerman.

Sherlock's gaze flickered to her for a moment. "Look," he murmured. "We don't need to interfere with your work, or see anything of consequence. All she needs is that we get a long enough look to confirm that you haven't murdered anyone. It should only take a moment. Just a glimpse inside will not compromise any confidentiality, and should calm her down considerably."

Ackerman looked up at Sherlock, looked back at the door, at Molly, then back at Sherlock. "All right. I'm not supposed to do this, but all right. Just let me go in first, five seconds, make sure- you know."

Sherlock nodded. "Of course."

Ackerman punched in the code and opened the door just wide enough to slip in. "Five seconds," he reminded Sherlock. Sherlock held the door, counted to five, and pushed it open.

The lab was set up for isolation work, for delicate atmospheric conditions or possible contagions. In the isolation chamber, two other doctors in coveralls looked up from pulling a sheet over something on a table. A notebook lay open on one of the counters. An agitator whirred. The lab was spotless, sterile. Ackerman spread his arms. "Well?"

Expectant eyes turned to Molly. She stared at the other doctors as the isolation door swished open to release them. "I- but they-" She took a step toward one of them, faltered, and sagged back against the wall by the door, looking as if she might burst into tears. "But I saw him... I saw you..."

"Saw what?" One of the doctors removed her mask, casting a confused and somewhat accusatory look at Ackerman. "James, what is she talking about?" He shrugged again.

Sally lay a hand on Molly's shoulder. "It's okay, Molly. Let's just give me the axe, now, okay? There's a good girl, now." Molly was reluctant to surrender the fire-axe, but eventually it was transferred into Sally's care.

"But I saw them..."

Ackerman clapped his hands, startling her. He gave them all a thin-lipped smile. "Well, now that our daily dose of insanity has been cleared up, would you all kindly clear out so we can go back to work?"

"Of course, sorry for the inconvenience," Lestrade started to say.

Sherlock, however, spoke over him. "I think not, actually. There are just a few points which are troubling me."

"What?" Sally said.

"Sherlock," John said warningly.

Ackerman's frustrated look returned. "What _are_ you on about? Look, you can see my colleagues right here." He took a step toward Sherlock.

"Don't touch him," Molly said.

Ackerman ignored her. "They quite obviously haven't been murdered," he was saying. "If you must, go get a warrant, but until then-" he took another step forward, extending a hand as if to physically herd Sherlock out.

As she had repeatedly proven in the last few minutes, Molly moved very quickly when she wanted to. She darted past Sally, and interposed herself between Sherlock and Ackerman, one hand raised to the latter's face, fingers wrapped around a little keychain-mounted cylinder. The aerosol hissed, releasing a fine spray of atomized mace into the doctor's eyes.

Things had already been moving along rapidly, but the next few seconds were chaos.

Arguably, Sherlock reacted first, with nearly preternatural reflexes. He wrapped both arms tight around Molly's midsection and threw himself backwards.

Ackerman reacted the moment the mace stung his eyes and activated a primal defence instinct. His face ripped open in the middle, the two sides pulling apart into a great gaping red maw lined with rows of wicked teeth. A thick, tentacle-like tongue whipped out and wrapped around Molly's wrist.

The other doctors screamed.

Sally, acting faster than she thought, hefted and swung the axe, neatly severing the tongue.

John and Lestrade both drew and fired. The Ackerman-monster roared, a horrible, impossibly inhuman sound, and leapt up onto the ceiling - no, less 'leapt', more like it somehow _fell_ up, and clung to the ceiling on its back.

As John and Lestrade continued to fire, everyone else scrambled out into the hall, and with one last shot the door was slammed shut. The thing's roaring continued, muffled.

"Jesus bloody Christ," Lestrade breathed.

"What the bloody cunting fuck was that?" Sally shrieked.

"Is there any other way for it to get out?" Sherlock said.

"Only one door," Molly said. "It has to know the code."

Sherlock jumped to his feet. "Get the door!"

The keypad flashed green. The door had hardly started to open before Lestrade, John, Sally, and the doctors were on it, shoving it shut again with their combined weight. Sally blocked the handles with the fire axe. The shrieking redoubled, and the doors bulged outward with a great loud _thump_, like the thing was throwing its entire weight against it. The barricaders pushed back.

"That's not going to hold it!" Lestrade called.

"I need something to pry this," said Sherlock at the keypad. "A screwdriver, knife, keys, anything!"

"Here!" Sally tossed him a swiss-army knife.

In short order, Sherlock had the faceplate open and the code scrambled. The pounding on the door did not cease, but they were able to all take a step back and breathe for a moment.

Well, until Molly took the opportunity to unwind the tongue from her wrist, and suddenly found teeth sinking into her skin. She yelped. "It's biting!" A solid yank managed to dislodge it. The tongue hit the linoleum with a fleshy _thwup_ and began to writhe, one end opening and closing a ring of bloody teeth. Spiderlike legs sprouted out of its sides. Lestrade snatched up a basin, emptied it onto the floor, and trapped the creature under it. John rushed to Molly to check the damage.

Sherlock folded his arms and inspected the gathering. His expression was stoic, but his eyes were bright, dancing with excitement. "John, Lestrade, Donovan," he said. "Keep an eye on our new friends here, please. They may not be what they seem." A tinny screech came from the basin. Sherlock's eyes practically glowed. "Shouldn't be possible..." he murmured. "I'll have to run some tests. Molly, I'm going to need a better way to transport that."

_x-X-x_

"Why did you believe me?" Molly was still white as a sheet, but she had stopped trembling, and only winced a little as John applied disinfectant to her wrist.

"Yes, I'm rather curious myself, Sherlock," John added.

Sherlock did not look up from the slide that he was preparing. They had found an organ transportation cooler in the supply closet and managed to transfer the tongue-thing into it with a pair of forceps, allowing for it to be transported safely to Sherlock's lab. Keeping it in place long enough to take samples had been an adventure in itself. The two doctors - one identified as 'Lourde', a tall, somewhat shapeless woman with a neat, feminine face, who was clearly older but whose smooth features belied an actual age count; the other 'Vick', a stocky, thick-necked thirty-something man with rimless rectangular eyeglasses and a curly black poof of a ponytail - had been relegated to a corner far from the door, Lestrade tasked with guarding them. Neither doctor had put up much of a fight, apparently still in shock over what their colleague had become. Sally was outside, stationed by the elevators and staircase with orders to stop anyone who tried to enter the basement.

Sherlock took his time in answering. Only once he'd gotten the slide into place did he murmur, "Molly said it had sprayed something at her. There's a mark on her left sleeve, just under the shoulder - something corrosive. It wasn't there this morning. Digestive acid, if I had to guess. The lab had been recently cleaned in several areas - 'recently' as in minutes before we walked in - but they missed several spots under the edges of the counters. Molly, the body you were going to show me - tell me about it."

"I only got a glimpse of it. The door wasn't entirely closed when they started opening the bag. It was burnt - badly burnt - but I've seen burnt bodies before. Not like that one. It looked... twisted. Mutated. Just... _wrong_, somehow. I didn't really have a clear idea of it, I still don't, it was just this bad feeling. I know that sounds silly..."

"Not at all," John assured her. "You know, all considered."

"Give me your spray." Sherlock leant in close as he spritzed pepper spray onto a tiny sample of flesh from the tongue-thing. He jumped about a foot when the sample screeched, upset its dish, and attempted to escape. Molly slammed a beaker over it before it could get far.

"What?" Lestrade demanded from across the room.

"Fascinating," was all Sherlock said, his eyes alight. "They're all alive. Every piece of it is a separate organism." Retrieving the sample with a pair of long-handled tweezers, he held it under the microscope. "It's not actually hurt. The capsaicin irritated it and it interpreted that as a threat, just as Ackerman did, and it reacted. The instinct must have bypassed his higher functions. But why..." He suddenly snatched up a clean slide and a scalpel and sliced his own hand, just under the thumb.

"Sherlock!" John cried in alarm.

"John, shut up, you'll break my concentration." Sherlock squeezed several drops onto the slide, added a single drop of the thing's blood, and then slid it under the microscope. While he adjusted with one hand, he held out the other for John to clean and bandage.

Thirty seconds of total silence followed, as everyone watched Sherlock and hardly dared breath. When he stepped away from the microscope, he didn't look triumphant - he looked troubled. "You said it was burnt?"

Molly nodded.

"What is it?" John said.

Vick spoke for the first time since they'd walked into the room. "Jesus, just tell us, what did you find?"

Sherlock didn't answer. Instead, he fished his phone out of his pocket, hit speed-dial, and held it to his ear.

"Mycroft? Shut up and listen. Get the HPA. I need a quarantine on St. Bart's with a military barricade, and I need it five minutes ago. Don't bother with guns - arm them with fire and electricity. Detain anyone that attempts to leave. Identify anyone who has left in the past hour and anyone they may have interacted with and detain all of them. Under _no_ circumstances is a guard to be alone with any number of detainees. And find out anything you can about a body transferred here confidentially last night."

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><p><em>To be continued.<br>_

_Another story to be blamed on the crack-muse, miss Adidasandpie, whom I described 'The Thing' to and who immediately suggested this. Once I had the image of Molly with a flamethrower in my head, I knew I had to write it._

_Beta-read by the aforementioned crack-muse.  
><em>

_Much love to Outpost 31, a 'Thing' fansite that helped me verify some stuff. I haven't seen the 2011 prequel, but I have read 'Who Goes There'._

__Logically, this would probably not happen, at least not like this, for a number of reasons, including that nobody would send that body to St. Bart's, and that I have no idea if Bart's would have any kind of 'confidentiality' procedures like this or would keep fire axes on the premises, much less in supply closets. But I wanted to write about Holmes facing off against the Thing, so I'm calling artistic license.__


End file.
